Biodiversity in communities

Question 1

SPEC: Define Species richness

Answer 1

Species richness is a measure of the number of different species in a community

Question 2

SPEC: Define an index of diversity

Answer 2

An index of diversity describes the relationship between the number of species in a community and the number of individuals in
each species.

Question 3

SPEC: What is the formula for a Biodiversity index

Answer 3

d = N( N − 1)/Σn( n − 1)
where N = total number of organisms of all species
and n = total number of organisms of each species.

Question 4

What happens as ecosystems develop overtime?

Answer 4

As ecosystems develop overtime they become complex communities with a high diversity index.

Question 5

How do Agricultural ecosystems differ from natural ecosystems?

Answer 5

In agricultural ecosystems, **farmers select for a few species with qualities that maximise agricultural product, reducing species richness and genetic diversity **(among the selected species), in favour of the most productive species with the most useful alleles.

Question 6

Describe the cascade of events that lead to reduced biodiversity in agricultural ecosystems

Answer 6

. Farmers select for a few species with qualities that maximise agricultural product
. There is limited biomass within the area, forcing non-desirable species to compete (intraspecific and interspecific) for the little resources remaining
. Most do not survive and those that do have reduced populations
. Species richness and Biodiversity decreases overtime

Question 7

How have farming practices intensified?

Answer 7

. Removal of hedgerows, grubbing out woodland
. Increased use of chemical fertilisers and pesticides
. Monocultures replacing natural diverse communities
. Overgrazing, leading to soil erosion and the prevention of natural communities from regenerating.
. Draining marsh or wetland and filling ponds
. Increased use of Biotechnology (mechanisation)
. Lack of intercropping, absence of crop rotation and undersowing

Question 8

Name conservation techniques for farming

Answer 8

. Maintain existing hedgerows
. Plant hedges rather than fences as field boundaries
. Crop rotation that includes nitrogen-fixing crop
. Reduced pesticide use via biological control or resistant GMOs
. Introduce Conservation headlands: areas at the edges of fields where pesticide use is restricted, enabling wildflowers and insects to flourish